The prolonged placement of insertable medical devices, such as needles and catheters, presents the risk of infection from bacteria and fungi at the site of insertion. Infection can result from the colonization of the insertion site by microorganisms present on the skin. The microorganisms can migrate into a patient's body along the outer surface of the insertable medical device resulting in infection.
The risk of infection is common with the use of urinary catheters for draining bodily fluids. Untreated infections can lead to infection of the kidneys. Infection typically results from manipulation of the catheter and drainage device. Virtually all patients undergoing long term urinary catheterization can develop bacteriurea. See Nicolle et al. Clin. Infect. Dis. (2005) 40(5), 643-654. Attempts to prevent urinary tract infection from long-term catheterization have produced mixed results. Jacobsen et al. Clin. Microbiol. Rev. (2008) 21, 26-59. Coating a catheter with an antimicrobial solution or lubricant has not proven successful. Limited trials with antibiotic-impregnated catheters, however, produced some benefit.
Infections can also result from the use of percutaneously inserted catheters and i.v. tubes. Catheter-related infections represent a significant proportion of hospital acquired infection and contribute to increased morbidity and mortality. Bouza et al. Clin. Infect. Dis. (2007) 44 (6), 820-26. General guidelines for prevention of infection include cleaning the area of insertion with an antiseptic such as 70% alcohol, tincture of iodine, or chlorhexidine. O'Grady et al. Clin. Infect. Dis. (2011) 52, pp. e1-e32. In spite of these preventive measures, prolonged placement of catheters can nonetheless result in infection.
Long term use of intravascular and urinary catheters is associated with the possibility of biofilm formation on the catheter. Microorganisms on the skin of a patient around a catheter insertion site can attach to the external surface and form a biofilm. Donlan, R. Clinical Infectious Diseases (2011) 52, 1038-1045; Trautner et al. Am. J. Infect. Control. (2004) 32, 177-183. Biofilms are microbial communities that colonize the surface to which they are attached and produce a gel-like extracellular polymeric substance matrix. Once established, organisms living in a biofilm can become much more resistant to antimicrobial agents than planktonic (i.e., freely suspended) organisms. Biofilms can also serve as a source of microorganisms that can subsequently infect a patient. Newman, D. Infectious Diseases Special Edition (2010) 13-20.
Current techniques used to impregnate drugs into materials to create drug eluting devices are limited in how much drug can be imbibed into the material. Current methods also require a large amount of drug to be unused and wasted during the imbibement process. Another drawback of using current imbibement/impregnation techniques is that drugs can elute more quickly than desired, thus decreasing the useful lifetime of the device.
Therefore, a need exists for novel devices and methods for preventing and reducing the incidence of infection at the site of insertion of an insertable medical device and inhibiting biofilm formation, particularly in the case of prolonged placement of a catheter.